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  • G01N2800/10—Musculoskeletal or connective tissue disorders

Definitions

• the present invention relates to a method of diagnosing 0 adolescent idiopathic scoliosis and related syndromes causing spinal deformities and a method for screening for a compound useful in the treatment of these diseases. More specifically, the present invention is concerned with a neuroendocrinal method of diagnosing adolescent idiopathic scoliosis and related syndromes causing spinal deformities and 5 a method for screening for a compound useful in the treatment of these diseases.
• AIS adolescent idiopathic scoliosis
• CNS central nervous system
• Dubousset suggested that AIS is probably caused by a proprioception control problem, a neuromuscular disorder in relation with the neurotransmitter involved with the bipedal condition.
• Muscles spindles are skeletal muscle sensory organs that provide axial and limb position information (proprioception) to the CNS. It has been proposed that muscle spindles act as muscle receptors involved in the detection of movement, both passive and active.
• Spindles consist of encapsulated muscles fibers (intrafusal fibers) that are innervated by specialized motor and sensory axons.
• Egr3-deficient mice lacked muscles spindles, a finding that is consistent with their profound gait ataxia.
• Egr3 is highly expressed in developing muscle spindles, but not in la afferent neurons or their terminals during developmental periods that coincide with the induction of spindle morphogenesis by sensory afferent axons. This indicates that type I myotubes are dependent upon Egr3- mediated transcription for proper spindle development. (7-9)
• Egr3-deficient mice lacked muscles spindles, a finding that is consistent with their profound gait ataxia.
• Egr3 is highly expressed in developing muscle spindles, but not in la afferent neurons or their terminals during developmental periods that coincide with the induction of spindle morphogenesis by sensory afferent axons. This indicates that type I myotubes are dependent upon Egr3- mediated transcription for proper spindle development. (7-9)
• Pax family of transcription factor in the capsules surrounding adult mouse muscle spindles where it may be implicated in the formation and maintenance of neuromuscular contacts within the muscle spindles throughout life.
• the present invention demonstrates for the first time that AIS patients exhibit a melatonin-signaling pathway impairment and that this impairment can be observed through various manifestations.
• the present invention demonstrates for the first time a dysfunction of melatonin-signaling in bone-forming, muscle-forming cells and blood cells of AIS patients.
• the present invention demonstrates for the first time that non-functional Gi proteins normally coupled to melatonin receptors MT1 and MT2 is related to such dysfunction.
• a method for diagnosing an increased risk for a disease characterized by a dysfunctional melatonin-signaling pathway in an animal comprising detecting the presence or absence of at least one impairment in melatonin-signaling pathway in at least one of the animal's cells, wherein the presence of at least one impairment in melatonin-signaling pathway indicates that the animal possesses an increased risk of developing said adolescent idiopathic scoliosis or other disease.
• the method of the present invention may also be advantageously used to diagnose a particular type of disease characterized by a dysfunctional melatonin-signaling pathway by determining whether the results of the assay correspond to those of a previously tested animal affected by this particular type of disease. For instance, it would be possible to determine with the method for diagnosing of the present invention, whether an animal is affected by AIS of group 1 , 2 or 3 (as described in Table 2 below) by determining its osteoblast responsiveness to melatonin treatment. This is particularly interesting if the most effective drug for treating or preventing AIS varies between the groups (1, 2 or 3). The method for diagnosing of the present invention therefore permits a better selection of the drug to be used for a particular patient.
• a method of screening for a compound useful in the treatment of a disease characterized by a dysfunctional melatonin- signaling pathway comprising the steps of contacting a candidate compound with at least one cell expressing at least one melatonin-signaling pathway impairment in the presence of a known melatonin-signaling pathway agonist, wherein the candidate compound is selected if said melatonin-signaling pathway impairment is reduced in the presence of the candidate compound as compared to that in the absence thereof.
• This method can be used for screening for compounds able to modulate melatonin-signaling impairment generally.
• the method of screening of the present invention may therefore be used to identify which compound is the most effective in counteracting the melatonin-signaling pathway impairment in a specific group of patients or in one patient in particular.
• a method of formulating a drug useful in the treatment of a disease characterized by a dysfunctional melatonin- signaling pathway comprising the steps of contacting a candidate compound with at least one cell expressing at least one melatonin-signaling pathway impairment, wherein the candidate compound is selected if said melatonin-signaling pathway impairment is reduced in the presence of the candidate compound as compared to that in the absence thereof, and formulating said drug with said selected candidate compound.
• the present invention discloses such compounds able to modulate melatonin-signaling pathway impairment including melatonin, forskolin and estradiol.
• the disease characterized by a dysfunctional melatonin-signaling pathway is adolescent idiopathic scoliosis or another disease involving spinal deformities. More specifically, the impairment may be detected by an accumulation of cyclique adenosine 5'-monophosphate (cAMP) in a cell of the animal, an absence of said cells proliferation in presence of the known melatonin-signaling pathway agonist, and a reduction of inhibition of osteoclasts resorption activity induced by the known melatonin-signaling pathway agonist, wherein the candidate compound is selected if said reduction of inhibition of osteoclasts resorption activity is inhibited in the presence of the candidate compound as compared to that in the absence thereof.
• cAMP cyclique adenosine 5'-monophosphate
• any cell from tissues targeted by melatonin or expressing melatonin signalisation and wherein other pathway members do not mask melatonin-signaling impairments may be used in accordance with the methods of the present invention.
• the cells used herein were selected in part for their accessibility. Hence, cells such as osteoblasts, osteoclasts, lymphocytes, monocytes and myoblasts are advantageously accessible and may conveniently be used in the methods of the present invention. Blood cells in particular are particularly accessible and provide for a more rapid testing.
• said known melatonin-signaling pathway agonist is melatonin, GTP or analogs thereof. Any other known melatonin-signaling pathway agonist may be used in accordance with the present invention.
• the known activator of adenylyl cyclase is forskolin.
• G proteins guanine nucleotide-binding proteins
• MT1 MelRla
• MT2 MelRlb
• MT1 is the receptor that mediates the reproductive and circadian responses to melatonin.
• the third receptor, MelRlc two isoforms ⁇ and ⁇
• MT3 has been first discovered based on its pharmacological properties that are quite distinct from the MT1 and MT2 receptor subtypes.
• estrogens are able to increase calmodulin expression, independently of both estrogens receptors (ER ⁇ and ⁇ ).(18) This is particularly interesting because calmodulin and melatonin exert a mutual antagonism, (19; 20) and membrane-bound calmodulin is able to interact with melatonin as demonstrated in Xenopus.(21) Moreover, melatonin has the property to destabilize the ERs DNA-binding on their cognate sequence. (22)
• melatonin up-regulates key osteoblasts terminal differentiation markers like osteocalcin (OC), osteopontin (OPN) and bone sialoprotein (BSP). This activation was already detectable after only 10 min of stimulation suggesting that melatonin stimulates osteoblast differentiation in vitro through specific interactions with one of its membranous receptors. It was then determined whether this transcriptional activation was mediated by MT1 or MT2 receptor subtype, and demonstrated that both receptor subtypes are expressed although time-course expression analysis revealed that MT2 receptor expression was predominantly detected. At the protein level, IHC experiments demonstrated the presence of both melatonin receptors at the cell surface.
• OC osteocalcin
• OPN osteopontin
• BSP bone sialoprotein
• Scoliotic and non-scoliotic pinealectomized chicken showed a similar and significant decrease in bone mineral density suggesting that bone tissue is indeed a target of melatonin action.
• EMG analysis performed with the same set of chicken showed a 75% increase in muscular tone of paraspinal muscles on both sides while a 60% asymmetrical increase of the muscular activity was measured on the left side, which correlated with the side of the scoliosis curve (99% left sided).
• melatonin-signaling pathway impairment or “dysfunction” is meant to refer to any impairment in this pathway that characterizes cells from' patients with AIS and related syndromes causing spinal deformities and includes but is not limited to: absence of inhibition of osteoclasts resorption activity, accumulation of cAMP in an animal cell, an hypofunctionality of Gi proteins, a phosphorylation state of Gi proteins distinct from that of normal cells, a absence of proliferation of certain cells in response to melatonin, a mutation in a gene encoding a member of the melatonin signaling pathway.
• control cells is used to refer to any cell not expressing the melatonin-signaling pathway of the cell under scrutiny. It includes cells from non-scoliotic animals and cells from animals displaying other types of scoliosis.
• analog thereof is meant to include any compound displaying the same activity as that for which the compound of reference is used.
• Gpp(NH)p is an analog of GTP.
• the cAMP accumulation may have been artificially induced by a known adenylyl. . cyclase activator such as forskolin and inhibited by an melatonin-signaling pathway agonist such as melatonin itself, or any agonist known for inhibiting cAMP accumulation such as GTP or Gpp(NH)p.
• a known adenylyl. . cyclase activator such as forskolin and inhibited by an melatonin-signaling pathway agonist such as melatonin itself, or any agonist known for inhibiting cAMP accumulation such as GTP or Gpp(NH)p.
• An absence of cAMP accumulation by these known agonists is interpreted as a melatonin-signaling impairment of the subject cell and of the animal from which the cell was isolated.
• the methods for diagnosing AIS and related syndromes causing spinal deformities in an animal comprises detecting any melatonin-signaling pathway impairment in at least one of the animal cells such as but not limited to lymphocytes, monocytes, osteoclastes, osteoblasts, myoblasts from the animal, and according to specific embodiments the animal is a human.
• candidate compounds to be tested according to the method of the present invention include non- peptides drug candidates (small molecules) as well as peptides targeting defective proteins involved in the melatonin-signaling pathway impairment, or oligonucleotides such as antisens molecules targeting a defective gene involved in the melatonin-signaling pathway impairment.
• Figure 1 graphically shows the inhibitory effect of melatonin on adenylyl cyclase activity in human normal osteoblasts and in AIS osteoblasts. Distribution of single data points obtained for each AIS patients and control subjects (congenital scoliosis, cong; and other scoliotic type, other/s) tested at physiological dose of melatonin (10 "9 M) on forskolin-stimulated osteoblasts. The black bars represent the mean of each group;
• Figure 2 graphically shows the inhibitory effect of melatonin on adenylyl cyclase activity in human normal osteoblasts and in AIS osteoblasts. Representative experiments showing the effect of increasing concentrations of melatonin (10 "11 to 10 "5 M) on forskolin-stimulated adenylyl cyclase activity in osteoblasts from control subject and patients with AIS (group 1 , 2 and 3). Data are expressed as mean ⁇ SEM;
• Figure 3 illustrates through photographs the detection of
• Each panel illustrates representative IHC experiments performed with MT1 receptor antibodies (upper panels) and MT2 receptor antibodies (lower panels) on primary human osteoblast cultures prepared from patients with AIS (AIS1-2) and compared with a control subjects;
• Figure 4 graphically shows the Gpp(NH)p inhibitory effect on adenylyl cyclase activity on human osteoblasts from patients with AIS and on control subjects. Distribution of single data points obtained for each AIS patients and control subjects in presence of Gpp(NH)p (10 "7 M) on forskolin- stimulated osteoblasts. The black bars represent the mean of each group;
• FIG. 5 illustrates through photographs the detection of Gi3 proteins coupled to MT2 receptors. Immunoblots were revealed with specific antibodies reacting with individual Gi with the exception of anti-Gi3 antibodies, which cross-react also with human Gi1 proteins. Note the presence of 60 kDa bands corresponding to phosphorylated Gi3 proteins. Lane 1 and 2 are from control subject (Marfan) not treated and treated with melatonin (10 "7 M) respectively. Lanes 3-4 and 5-6 come from two different AiS patients. Lanes 7-8-9 are positive control peptides for Gi1 , Gi2 and Gi3 respectively;
• Figure 6 graphically shows the proliferation of human normal osteoblasts and that of AIS osteoblasts through time-courses of [3H]thymidine uptake;
• Figure 7 shows the expression analysis of melatonin receptors in human osteoblasts
• Figure 8 shows the effect of Gpp(NH)p (10 "7 M) on forskolin-stimulated adenylyl cyclase activity in osteoblasts from control subjects and in osteoblasts from patients with AIS. Distribution of single data points obtained from each patient with AIS and control subjects tested;
• FIG. 9 shows Gi proteins coupled to MT2 melatonin receptor. Black and white arrows correspond to unphosphorylated and phosphorylated forms of Gi proteins respectively;
• Figure 10 shows the detection of phosphoserine residues in phosphorylated Gi proteins.
• the immunoblot in Fig. 9 was stripped and reprobed with antibodies recognizing antiphosphoserine residues. Numbering corresponds to cell cultures conditions: 1) untreated; 2) with melatonin; 3) with Na3V04, a tyrosine phosphatase inhibitor; and 4) with genistein, a tyrosine kinase inhibitor;
• Figure 11 graphically shows the bone mineral density in scoliotic and control chicken
• Figure 12 graphically shows the bone mineral density in scoliotic and control chicken in four different plans
• Figure 13 graphically shows EMG activity in paraspinal musculature of pinealectomized chicken
• Figure 14 graphically shows EMG activity in paraspinal musculature of pinealectomized chicken in movement
• Figure 15 graphically shows the inhibitory effect of melatonin on adenylyl cyclase activity in human normal myoblasts and in AIS myoblasts;
• Figure 16 illustrates through photographs the detection of
• MT1 and MT2 melatonin receptors in human osteoclasts from normal human subjects.
• Panels labeled MT1 and MT2 represent corresponding receptor subtype detected by IHC with specific primary antibodies and distinct secondary antibodies conjugated to different fluorochromes (red, phycoerythrin; green, FITC).
• the panel labeled h-OC corresponds to a human surface antigen specific for mature osteoclasts. Negative control has been generated by omission of the primary antibodies;
• Figure 17 illustrates through photographs the detection of MT1 and MT2 melatonin receptors in human osteoclasts from AIS human patients.
• Panels labeled MT1 and MT2 represent corresponding receptor subtype detected by IHC with specific primary antibodies and distinct secondary antibodies conjugated to different fluorochromes (red, phycoerythrin; green, FITC).
• the panel labeled h-OC corresponds to a human surface antigen specific for mature osteoclasts. Negative control has been generated by omission of the primary antibodies;
• Figure 18 graphically shows the measurement of osteoclasts activity (pit resorption assay) on bone matrix.
• the inhibitory effect of melatonin on osteoclasts activity was performed using normal human osteoclasts derived from peripheral blood.
• Figure 19 graphically shows the effect of estrogen on the melatonin-signaling pathway impairment of patients with AIS
• Figure 20 shows Gi proteins coupled to MT2 melatonin receptor.
• the cells used were prepared from human MG-63 osteoblast culture (panel A) and osteoblast cultures from AIS patient (case 22 of Table 1 , panel B); and
• Figure 21 shows Gi proteins coupled to MT2 melatonin receptor.
• the cells used were prepared from osteoblast cultures from AIS patient.
• Panel A case 37 of Table 1
• panel B case 29 of Table 1.
• Osteoblast and myoblast cultures prepared from specimens obtained intraoperatively during spine surgeries were used to test the ability of melatonin and Gpp(NH)p, a GTP analogue, to block cAMP accumulation induced by forskolin.
• melatonin receptors and Gi proteins functions were evaluated by immunohistochemistry, binding assays with [ 125 l]-iodomelatonin and by co-immunoprecipitation experiments.
• AIS adolescent idiopathic scoliosis ; R, right ; L, left; na, not available; NF, neurofibromatosis Basal and induced cAMP values are given as pmoles/1 x10 5 cells
• EXAMPLE 3 Isolation of human osteoblasts [0055] Osteoblasts were obtained intraoperatively from bone fragments reduced in smaller pieces mechanically with a bone cutter in sterile conditions and incubated at 37 Q C in 5% CO 2 in a 100 mm culture dish in presence of DMEM medium containing 10% FBS (certified FBS, Invitrogen, Burlington, ON, Canada) and 1% penicillin/streptomycin (Invitrogen). After a 30-day period, osteoblasts emerged from the bone pieces were separated at confluence from the remaining bone fragments by trypsinization.
• FBS certified FBS, Invitrogen, Burlington, ON, Canada
• penicillin/streptomycin Invitrogen
• EXAMPLE 4 Assay for detecting melatonin-signaling pathway in AIS osteoblasts- cAMP accumulation using melatonin as known agonist of the melatonin-signaling pathway
• Osteoblasts from patients with AIS and control subjects were seeded in quadruplet on 24-wells plate (1x10 5 cells/well) and incubated either with the vehicle alone, dimethyl sulphoxide (DMSO, Sigma, Oakville, ON, Canada) or the diterpene forskolin (10 "5 M, Sigma) to stimulate the cAMP formation.
• Inhibition curves of cAMP production were generated by adding melatonin to the forskolin-containing samples in concentrations ranging from 10 "11 M to 10 "5 M in a final volume of 1 ml of DMEM media with 0.5% bovine serum albumin (BSA, Sigma).
• cAMP content was determined in 200 ⁇ aliquot of the supernatant using an enzyme immunoassay kit (Amersham-Pharmacia Biosciences, Mississauga, ON, Canada). All assays were performed in duplicate.
• melatonin produced a dose-dependent inhibition of forskolin-stimulated adenylyl cyclase activity detectable by a reduction of cAMP levels of about 60-70% (Fig.1-2).
• osteoblasts from patients with AIS showed a lack of inhibition of forskolin-stimulated adenylyl cyclase activity by melatonin (Fig.1-2).
• the distributions of single data points obtained with patients with AIS, in comparison with control subjects are reported in Figure 1. Further analysis allowed classifying patients with AIS into 3 distinct groups according to their osteoblast responsiveness to melatonin treatment (Fig. 2).
• melatonin increased cAMP accumulation in treated osteoblasts, which contrasted with the normal inhibitory values obtained with control subjects (Fig. 2).
• osteoblasts did not response to melatonin since no significant inhibition of cAMP accumulation was observed even at pharmacological dose (10 "7 M) or higher (10 "5 M) as illustrated by the cAMP curve inhibition (Fig. 2).
• the third group showed only a weak response toward melatonin treatment, although at physiological dose (10 " 9 M) no significant inhibition was measured (Fig. 2).
• basal and induced cAMP levels increased from group 1 to group 3 when compared to control subjects (data not shown).
• EXAMPLE 5 Assay for detecting melatonin-signaling pathway impairment in AIS osteoblasts- cAMP accumulation using GTP or Gpp(NH)p as known agonists of the melatonin-signaling pathway
• Gpp(NH)p guanilyl 5'-imidophosphate, Sigma
• Results from the cAMP accumulation assays are given as the mean ⁇ SEM. Data were analyzed with StatView software.
• RNA isolated every 2 h during a 24 h cycle from MC3T3-E1 cells treated (+) or not (-) with melatonin (10 "7 M).
• FIG. 7 represents a similar analysis with osteoblast cultures obtained from one scoliotic patient (AIS female, 15 year old) and a non- scoliotic subject (NS female, 15 year old) without (c) and with melatonin (m, 10-7M).
• PCR products were separated on a 1.5% agarose gel and visualized by ethidium bromide staining. Note that both melatonin receptor subtypes are expressed in MC3T3-E1 cells and in human osteoblasts but in MC3T3-E1 cells, only MT1 subtype is down regulated in presence of melatonin while MT2 subtype is the predominant form. No significant difference was observed between AIS and NS subjects. Expression analysis by RT-PCR and IHC experiments indicated no significant variation in melatonin receptor levels although it cannot be ruled-out that their function could be altered in AIS.
• Radioligand-binding assays with 2- 125 l-iodomelatonin and IHC assays with MT1 and MT2 specific antibodies were performed to assess whether the dysfunction of melatonin-signaling observed could be secondary to either a reduced level of melatonin receptors or to mutations affecting their function.
• Receptor subtype localization and distribution were determined in osteoblastic cells by immunohistochemistry (IHC) assays with anti- human MT1 and anti-human MT2 antibodies (kind gifts from Prof. F. Fraschini and Dr D. Angeloni, University of Milan, Italy).
• IHC immunohistochemistry
• Presence of coupled Gi proteins in respective immune-complexes were determined by SDS-PAGE and Western blot with specific Gi antibodies (Santa Cruz Biotechnology Inc., Santa Cruz, CA, USA) and phosphorylation status of these coupled Gi proteins were determined using anti-phosphoserine, phosphothreonine and phosphotyrosine antibodies (Sigma) using the same membrane after stripping. Purified recombinant Gi proteins were used as control for antibody specificity
• Figure 20 also illustrate how the phosphorylation pattern of cells isolated from patients with a melatonin-signaling impairment differs from those of control cells.
• Identification of Gi proteins coupled to MT2 melatonin receptor were performed with specific anti-MT2 antibodies using purified membrane fractions prepared from human MG-63 osteoblast culture (panel A) and osteoblast cultures from AIS patient (case 22, panel B) treated overnight in different conditions: 1-5-9) untreated; 2-6-10) with melatonin; 3-7-11) with Na3VO4, a tyrosine phosphatase inhibitor; and 4-8-12) with genistein, a tyrosine kinase inhibitor.
• the affinities of the three Gi proteins to the MT1 and MT2 receptors enabling them to be associated and pre-coupled to these receptors differ.
• the Gi3 has the strongest affinity to these receptors in absence or presence of melatonin, followed by Gi2 and then Gi1. In both conditions, only a weak interaction of Gi1 protein was detected with both receptor subtypes. Interestingly, in absence of melatonin, 2 forms of Gi3 and Gi2 proteins were detected suggesting that one of these forms could be phosphorylated (Fig.12).
• overnight treatment of the cells with melatonin or genistein (a tyrosine kinase inhibitor) completely abolished the presence of both phosphorylated forms in MT1 or MT2 immune complexes. This suggests that a tyrosine phosphorylation regulates indirectly Gi proteins functions through the activation a downstream unknown serine kinase.
• GTP and Gpp(NH)p could be triggered by post-translational modifications of Gi proteins involving serine residues phosphorylation.
• Phosphorylation of Gi proteins at their N-terminus is well known to block the formation of functional heterotrimers with G ⁇ and Gy subunits preventing the inhibition of adenylyl cyclase activity either in presence of melatonin or Gpp(NH)p.
• Myoblasts were obtained intraoperatively from normal and AIS patients and enzymatically dispersed, incubated, separated and put into cultures according to methods known in the art.
• EXAMPLE 13 Assay for detecting melatonin-signaling pathway impairment in AIS myoblasts- cAMP accumulation using melatonin as known agonist of the melatonin-signaling pathway
• melatonin signaling is assessed by investigating the ability of Gi proteins to inhibit stimulated adenylyl cyclase activity in intact skeletal myoblasts.
• Cells prepared from patients with AIS and control subjects are seeded in quadruplet on 24-wells plate (1x10 5 cells/well) and incubated either with dimethyl sulphoxide (DMSO, Sigma) or forskolin (10 "5 M, Sigma) to stimulate the cAMP formation.
• DMSO dimethyl sulphoxide
• forskolin 10 "5 M, Sigma
• cAMP content is determined in 200 ⁇ aliquot of the supernatant using an enzyme immunoassay kit (Amersham- Pharmacia Biosciences).
• Gi proteins The functionality of Gi proteins is assessed by investigating their ability to inhibit adenylyl cyclase activity in myoblasts isolated from patients with AIS and control subjects.
• Gpp(NH)p the non-hydrolysable analogue of GTP
• Gpp(NH)p guanilyl 5'- imidophosphate, Sigma
• Basal cAMP levels is obtained from untreated cells, while cells tested with forskolin alone corresponds to the induced levels. Standard curve for sensitivity and quantification is performed with standards provided by the manufacturer of respective assays. (23)
• EXAMPLE 15 Statistical analysis for assays with myoblasts [0083] Results from the cAMP accumulation assays are given as the mean ⁇ SEM. An analysis of variance (ANOVA), followed by Fisher's protected least significant difference (PLSD) procedure for post- hoc comparison is used to verify the significance between 2 means.
• ANOVA analysis of variance
• PLSD protected least significant difference
• the cells are resuspended in Tris (50 mM, pH 7.4) buffer and then added to tubes containing 500 pM of 2- [125l]iodomelatonin in the absence (total) or presence (non-specific) of melatonin (1 ⁇ M) in a final reaction volume of 0.26 ml.
• Cells are then incubated for 1 h at room temperature and harvested by filtration over glass filters (Millipore) pre-soaked in 10% polyethylenimine (Sigma) and counted in a gamma counter. All reactions are run in duplicate. The data is expressed as femtomoles of receptor per milligram of protein. Protein determination is made by the method of Bradford using the BioRad protein assay reagents (BioRad).
• IHC experiments are performed with polyclonal antibodies reacting specifically with either the MT1 or MT2 receptor subtypes (kind gift from Dr Debora Angeloni and Prof Franco Fraschini, University of Milan, Italy) using a confocal microscope.
• IHC experiments are performed with primary cell cultures treated with a physiological dose of melatonin (10 _9 M) or estradiol (10 "10 M).
• Negative control for IHC is generated by omitting the primary antibody and by competition with specific blocking peptide.
• Positive controls are provided for IHC experiments and binding assays using stably transfected C2C12 myoblastic cells expressing constitutively MT1 or MT2 receptor. Specificity of each antibody has been already tested with human osteoblasts.
• binding assays with f125l]iodomelatonin subtraction of nonspecific binding obtained in presence of melatonin from the total binding generated with the radioligand alone determines the specific binding.
• MT1 and MT2 can bind this radioligand with almost the same affinity.
• luzindole 10 M
• MT2 antagonist a MT2 antagonist
• All assays are performed in duplicate. Data obtained in total binding assays with the radioligand is analysed by Student's unpaired t-test. Significance is defined as P ⁇ 0.05, and data will be analysed with StatView and Statistica softwares. [0088] It cannot be ruled-out at this stage that scoliotic patients could display a distinct distribution of melatonin receptors.
• reduced receptor binding in situ could indicate potential interference by an unknown factor (calmodulin, estrogens etc.), that could be easily correlated at least for the estrogens by similar assay in vitro.
• a marked reduction of 2- [ 125 l]iodomelatonin binding in scoliotic sections could be caused by either a reduction in the number of a specific receptor subtype or a by a mutation reducing the affinity of this receptor. It is unlikely that the presence of serum in the in vitro binding assay may interfere with this assay since 10% FBS should contain less than 10 "11 M of melatonin.
• Muscle cells are grown to confluence in 10 cm tissue culture dishes, rinsed once with ice-cold PBS, and scraped off their plastic support. After sedimentation, the cell pellet are resuspended in 2 ml of buffer A (5mM Tris-HCI pH 7.4/ 2mM EDTA/protease inhibitors cocktail) and subsequently disrupted by sonication. Then, membranes are sedimented by centrifugation 450 xg/5 min at 4 g C and the supernatant added on the top of 9 ml 35% sucrose cushion. Membranes will be sedimented by ultracentrifugation at 150,000 xg/90 min. Purified membrane fraction sediment at the bottom of the sucrose cushion.
• buffer A 5mM Tris-HCI pH 7.4/ 2mM EDTA/protease inhibitors cocktail
• Membrane fractions are resuspended in 1 ml of buffer B (50mM Tris-HCI pH 7.4/5mM MgCI2) and incubated with or without ligand (melatonin) for 1 h at 25 e C. For ligand-stimulated samples, all subsequent steps are performed in the continued presence of ligand. Thereafter, membranes are centrifuged at 18,000 xg/30 min at 4 ⁇ C and washed once in 1 ml buffer C
• Immunoprecipitation of solubilized melatonin receptors are performed with gentle agitation overnight at 4 S C with antibodies (1 :40) reacting specifically with either human MT1 or MT2 subtypes (kind gifts of Dr Debora Angeloni and Pr Franco Fraschini, Milan University, Italy), followed by a 6 h incubation at 4 S C with 50 ⁇ l of Protein-A agarose suspension (Sigma) to immunoprecipitate by centrifugation the individual melatonin receptor.
• G proteins are dissociated from immune complexes by treatments with Gpp(NH)p (0.1 mM) for 1 h at 37 e C and are separated by 12% SDS-PAGE and transferred to nitrocellulose membranes.
• Immunoblot are carried-out in TBST buffer containing 5% skim milk with commercially available antibodies recognizing individual Gi proteins (GM-3, Santa Cruz) and reactive bands are visualized using enhanced chemiluminescence.
• similar assays are performed with purified membranes from cells treated overnight or less with physiological doses of melatonin, estradiol or with different kinase and phosphatase inhibitors such as tyrosine kinase inhibitors, tyrosine phosphatase inhibitors and PKC specific inhibitors. Additional immunodetection is performed with antibodies reacting against Gz proteins, a related Gi family member.
• EXAMPLE 18 Assay for detecting melatonin-signaling impairment in osteoblasts - proliferation assay [0090] An assay was performed to compare the proliferation of osteoblasts of normal subjects with that of scoliotic patients. In Figure 6,
• Panel A represents time-courses experiments (triplicates) of [3H]-thymidine incorporation (cpm values in abscise axis) in human osteoblasts generated from bone specimens isolated from normal (NS) subject (F1/female 17 years old) and scoliotic patients (AIS M2/male 18 years old and F1/female, 17 years old) stimulated by a physiological dose of melatonin (10 "9 M) used as known agonist of the melatonin-signaling pathway.
• This assay showed that normal osteoblasts growth rate increases linearly in response to a physiological dose of melatonin (10 "9 M) while those from scoliotic patients did not respond to melatonin.
• EXAMPLE 19 Assay for detecting melatonin-signaling impairment in lymphocytes - cAMP accumulation using melatonin as known agonist of the melatonin-signaling pathway
• Anticoagulant-treated blood was layered on the Ficoll-Paque solution and centrifuged for a short period of time. Differential migration during centrifugation resulted in the formation of layers containing different blood cells. Because of their lower density, the lymphocytes were found at the interface between the plasma and the Ficoll-Paque with other slowly sedimenting particles (platelet and monocytes). The lymphocytes were then recovered from the interface and subjected to a short washing step with a balanced salt solution to remove any platelets, Ficoll-Paque and plasma. Then, the cells were counted and used to perform the cAMP assays described in Examples above. As is known from the litterature, the lymphocytes have melatonin receptors at their surface. Results could be obtained in 3 h or less with this particular assay. This assay is advantageously rapid as compared to assays using osteoblasts (at least a month) because they do not require culture time. EXAMPLE 20
• osteoclasts derived from monocytes/lymphocytes fraction isolated from peripheral blood of AIS patients and control subjects are performed.
• Primary osteoclasts are derived from the peripheral blood of patients and non- scoliotic subjects using 10 ml of blood or less.
• Anticoagulant-treated blood is layered on the Ficoll-Paque solution and centrifuged for a short period of time. Differential migration during centrifugation results in the formation of layers containing different blood cells. Because of their lower density, the lymphocytes are found at the interface between the plasma and the Ficoll-Paque with other slowly sedimenting particles (platelet and monocytes).
• the lymphocytes are then recovered from the interface and subjected to a short washing step with a balanced salt solution to remove any platelets, Ficoll-Paque and plasma.
• the cells are then counted and seeded at high density (1x10 6 cells per cm 2 ) onto artificial bone or dentin matrix in ⁇ -MEM with 10%FBS and antibiotics. After a few days, cells that remain adherent will start to differentiate into osteoclasts, forming large multinucleate cells after 15-20 days. Addition of melatonin (10 '9 M to 10 "7 M) inhibits osteoclasts resorption activity, which is visualized by the absence of resorption pit in the bone matrix (i.e. absence of holes or fewer holes on the surface).
• a method of screening of the present invention was performed and identified estrogen as one compound able to modulate the melatonin-signaling pathway impairment in AIS patients.
• Experiments were perfomed showing the effect of increasing concentrations of melatonin (10 " 1 to 10 "5 M)used as known agonist of melatonin-signaling pathway on forskolin-stimulated adenylyl cyclase activity in osteoblasts from two patients with AIS (group 3 see Table 2) treated or not with a physiological dose of estradiol (10 "10 M).
• Results illustrated in panels A and B of Figure 19 correspond to AIS patient numbered 13 and 29 in Table 1, respectively. It is apparent from this figure that the treatment with a physiological dose of estrogen (oe) is sufficient to further block the inhibitory effect of melatonin in scoliotic patients belonging to the AIS group 3 (see table 2).
• the chickens were exhibiting a scoliosis 7-days post-pinealectomy, while in Figure 12, they were exhibiting a scoliosis 21 -days post-pinealectomy.
• Treatment with melatonin, 3mg/kg/day ip increased BMD in treated animals.
• EMG measurement of paraspinal musculature activity using intra-muscular electrodes revealed a 75% bi- lateral increase in muscular tone in scoliotic pinealectomized chicken at rest when compared to sham or non-scoliotic pinealectomized groups (Fig. 13).
• EMG analysis was performed with implanted electrodes 21 -days post- pinealectomy. EMG activities were recorded in active chicken and compared between sham and scoliotic pinealectomized chicken. Determination of EMG activity at rest in paraspinal musculature of pinealectomized chicken.

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